Summary EFFECT OF RAINFALL VARIABILITY, WATER DEMAND AND STORAGE SIZE ON THE HARVESTED RAINWATER IN ESWATINI

GSRJ VOLUME 3 ISSUE 1 (DECEMBER 2016 – FEBRUARY 2017) ISSN : 2349-9397


A PEER REVIEWED INTERNATIONAL
JOURNAL OF GLOBAL SCHOLASTIC
RESEARCH JOURNAL

GSRJ
GLOBAL SCHOLASTIC RESEARCH
JOURNAL OF MULTIDISCIPLINARY


EFFECT OF RAINFALL VARIABILITY, WATER DEMAND AND STORAGE SIZE
ON THE HARVESTED RAINWATER IN SWAZILAND

J.I. MATONDO1; S.S. SINGWANE2
1
Department of Geography, Environmental Science and Planning, University of Swaziland
P/B Kwaluseni Swaziland
2
Department of Geography, Environmental Science and Planning, University of Swaziland
P/B Kwaluseni Swaziland

Abstract
A study to assess the effect of rainfall variability, varying water demand and storages sizes on
the duration of the collected rainwater for domestic purposes in the drought prone areas of
Swaziland was conducted in the Lowveld region. The choice of the Lowveld was motivated
by the fact that it is prone to drought and experiences acute water shortage problems. The
objectives of the study were to determine the: (i) effect of rainfall variability on the annual
amount of rainwater to be collected (ii) effect of varying the water demand on the duration of
water use of the harvested rainwater (iii) effect of varying the size of water storage facilities
on the duration of water use of the harvested rainwater. Rainfall data was collected from the
Meteorology Department. The study shows that the amount of rainfall in the Lowveld region
of Swaziland decreases considerably from north to south. The findings also reveal that there
is a direct relationship between size of storage device, level of water use per day, and
duration of use of the collected rainwater. The relationship is that when you increase the level
of water use, the duration of use of the collected rainwater is shortened. However, if the level
of water use is not increased while the size of the storage facility is increased, the collected
rainwater is able to sustain the demand for a two year consecutive period without any
shortages. However, when the level of water use was increased to 4500 L/month with the
storage size of 10000 L/month the collected rainwater was not able to meet the demand and
the duration of the water use decreased from north to south of the Lowveld region.

Keywords: Rainwater harvesting; Rooftop; Lowveld region; water demand; Storage device;
duration of water use

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, GSRJ VOLUME 3 ISSUE 1 (DECEMBER 2016 – FEBRUARY 2017) ISSN : 2349-9397

1.0 INTRODUCTION
Swaziland enjoys a subtropical climate that is characterised by hot and wet summers and cold
and dry winters. Variations in climatic conditions occur within the six physiographic regions
(Figure 1) giving rise to three clearly distinguishable climate types (i.e. Cwb, Cwa. and Bsh).
Highveld and Upper Middleveld are characterized by a Cwb climate. Cwb is a mild humid
climate with a dry winter and warm summer with the warmest month below 22oC (Strahler
and Strahler, 1992). Lower Middleveld and Lubombo range have a Cwa climate whilst the
Western and Eastern Lowveld have a Bsh climate (Murdoch, 1970).




Figure 1: Physiographic regions of Swaziland
Source: National Meteorological Service (2004)

Cwa is a mild humid climate with a dry winter and a hot summer with warmest month over
22oC. Bsh is a semiarid climate which is dry-hot with a mean annual temperature over 18oC
(Strahler and Strahler, 1992). Mean annual rainfall ranges from about 1500 millimetres in the
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